Zinc and cadmium hyperaccumulation by Thlaspi caerulescens from metalliferous and nonmetalliferous sites in the Mediterranean area: implications for phytoremediation

Abstract

Growth, tolerance and zinc and cadmium hyperaccumulation of Thlaspi caerulescens populations from three metal contaminated soils and three normal soils were compared under controlled conditions. Individuals of six populations were cultivated on five soils with increasing concentrations of zinc (50-25 000 µg g −" ) and cadmium (1-170 µg g −" ). There was no mortality of normal soil populations in the four metal-contaminated soils, but plant growth was reduced to half that of populations from metal-contaminated soils. However, in noncontaminated soil, the growth of individuals from normal soils was greater than that of individuals from metal-contaminated soils. Individuals from normal soils concentrated three times more zinc in the aboveground biomass than those from metal-contaminated soils, but the latter accumulated twice as much cadmium. We conclude that populations of T. caerulescens from both normal and metal-contaminated soils are interesting material for phytoextraction of zinc and cadmium, but to optimize the process of phytoextraction it is necessary to combine the extraction potentials of both type of populations.

Phytoremediation of urban soils contaminated with trace metals using Noccaea caerulescens: comparing non-metallicolous populations to the metallicolous ‘Ganges’ in field trials

“…CAL and NMET ecotypes have different metal-related traits. When grown in the same substrate, NMET accumulate more Zn (about twice) and Ni than CAL (Escarré et al 2000;Meerts and van Isacker 1997), and NMET can reach 20,000 μg g −1 of Zn on moderately contaminated substrates (Dechamps et al 2007). On the other hand, high Cd CAL populations from South of France (such as Saint-Félix or Ganges) have been identified for their great potential of Cd phytoextraction, as they can accumulate up to 1000 μg g −1 (Hammer and Keller 2003;Lombi et al 2001;Robinson et al 1998;Zhao et al 2003), compared to 300 μg g −1 for NMET .…”

“…caerulescens (Brassicaceae, formerly Thlaspi caerulescens) is one of the most promising candidate species for Cd and Zn phytoextraction (Koopmans et al 2008;Maxted et al 2007;McGrath et al 2006;Zhao et al 2003). Three ecotypes of N. caerulescens have been described: metallicolous plants grow in soils enriched in Cd-Zn-Pb (calamine, CAL) and in serpentine sites (mostly enriched in Ni), whereas non-metallicolous (NMET) grow in uncontaminated soils (Escarré et al 2000;Meerts and van Isacker 1997;Molitor et al 2005;Reeves et al 2001). CAL and NMET ecotypes have different metal-related traits.…”

“…The potential efficiency of phytoextraction with N. caerulescens has first been tested in pot trials using soils spiked with metals or from polluted field sites (e.g., Robinson et al 1998;Escarré et al 2000;Keller and Hammer 2004). These studies concluded that phytoextraction offers a great potential for Cd and Zn remediation achievable in a few crops for moderate soil concentrations.…”

“…Experimental design and plant cultivation N. caerulescens seeds came from three populations: two NMET from the Grand Duchy of Luxemburg, Wilwerwiltz and Goebelsmühle (hereafter WIL and GOE) (Molitor et al 2005), and one metallicolous Ganges (GAN, or BAvinières^) from St-Laurent-le-Minier, France (Escarré et al 2000). Seedlings of N. caerulescens were grown in greenhouse for 2.5 months before transplanting in the field.…”

“…This study has confirmed for the first time in field trials the interest of using NMET populations of N. caerulescens for Zn phytoextraction. Their higher potential for Zn extraction had already been shown (Meerts and van Isacker 1997;Escarré et al 2000) but had never been tested in the field. The average metal uptake of NMET was 27 kg Zn ha −1 , compared to 11 kg Zn ha −1 for GAN.…”